Unfortunately, there is no set formula or signature for marriage or childbirth, although others may disagree, apparently horary and vedic seem confident in this area. There are indicators and potential as there would be with natal, solar return chart but guarantees -- (post 2 & 3 below)
http://www.astrologyweekly.com/forum/showthread.php?p=207744#post207744

Your chart is a blueprint of your personality, facets and penchants and the whole chart is 'potential' for development. There is nothing guaranteed or fatalistic in charts, I do believe we still do have free will. I also believe we chose our parents and childhood circumstances best suited to learning those Lessons in the best way we can.

I think it's worth bearing in mind that the natal chart, like solar returns is all about 'potential' but as we all know we don't always fulfil that potential do we.

It's like someone saying you can predict death, but with modern medicine and sciences the way they are and the potential to 'die' three times in a life, doesn't mean to say you will does it  

I think lots of people have unrealistic expectations about what astrology can and can't do. astrology is an 'art, science and craft' and not clairvoyance either. If there were a formula or signature, don't you think we would ALL be using it?

What Astrology Can and Can Not Do
http://www.ofspirit.com/susanmiller1.htm
http://www.cafeastrology.com/articles/whatastrologycandoforyou.html

Moved to the Western astrology reading forum,

site moderator

Transits
I use--- 1° approaching, 1° exact and 1° departing. If you click on the link listed below for the online ephemeris it will list all planets at any given time. Learning astrology is like learning a new ‘language’ and obviously the more effort you put into something the more your knowledge and understanding will increase. All transits act as ‘background’ influences through a house, until it makes a mathematical aspect to a planet inside or an Angle.

For 'timings' I would look to the retrograde hit as the most important trigger, then look to see what the quicker planets are doing especially mars & mercury --

astro.com has fee six month transit forecast plus when you get into Extended chart selection, look at the three tabs after calculating a chart under ‘method’ default is circular wheels (on left), middle is special charts and in their you get graphic ephemeris 1yr (or 5years) with natal = transits for 1yr and lots more. BUT you first must learn or memorise the 'glyphs' ie: shorthand for recognising what these maps/graphics mean.

For example when you post or reply to a chart the 'smilies' to the right and just under them [more] if you click on there it will bring up a whole loads of 'glyphs'  Mercury  Uranus  conjunction (+or - 8')  trine aspect 120'  Libra
http://cafeastrology.com/transits.html
http://cafeastrology.com/transits_2.html
http://www.bobmarksastrologer.com/transits18.0.htm
http://www.astro.com/faq/fq_fh_transits_e.htm
http://www.astro.com/astrology/in_transits_e.htm
http://www.astro.com/swisseph/ae/2000/ae_2009.pdf
http://www.khaldea.com/ephemcenter.shtml
http://www.astrologyweekly.com/learn-astrology/astrology-glyphs.php
http://www.dkfoundation.co.uk/dkfoundation/BookTransitsAndProgressions.htm

Now it's more important to focus on transits from Jupiter to Pluto (poss mars as this is the ignition key)and these planets when aspecting something in your natal chart 'set off' the difficult or nice 'aspects - potential - problems' that your chart expresses. By that I mean if a benefic planet like Jupiter hits/touches/transits your venus, mars or uranus these could be experienced very pleasantly. BUT if your natal venus is afflicted, or badly aspected say conj saturn then jupiter will not has such a good effect. It all depends on how the natal planet is 'aspected'  

For me I would say external 'events' must be seen by transits, progressions or Solar arcs to Angles ie: Asc/Desc & MC/IC most other times these events are 'internal, psychological matters as in between the ears'

Now astro.com uses a much wider orb, possibly something like 5° or even 10° that’s why when you use the free transit forecast service a transit goes on for months and months. BUT common sense should tell you when the transit is ‘exact’ then it’s at the strongest. Some astrologers swear by 1° approaching produces ‘events’ some say the 1° exact, some say 1° off for triggering events. I personally look to the exact and 1° off for ‘timings’ especially the retrograde hit (backwards hit)